Container of variable volume

Abstract

A container of variable volume is disclosed consisting of parallel spaced polygon surfaces peripherally interconnected via triangular surfaces which join one another. The triangular surfaces are shaped and interconnected such that when the two polygons move relative to one another they undergo a rotational movement relative to one another. The triangular surfaces may, in place of having their ends attached to the polygons, be attached to a further set of triangular surfaces whereby the stack height of the container may be incrementally increased. Fold-up containers as herein disclosed may be used as ink supply containers for ink recording devices.

I claim as my invention: 
     
       1. A closed variable volume container with stable wall components connected by fold lines accomodating uniform folding of the wall components to collapse the container to a substantially no volume enclosure which comprises a pair of opposed end walls of equilateral polygonal shape positioned in parallel planes, one of said end walls being rigid and having a dispensing outlet, an intermediate peripheral wall connecting said end walls adapted to fold to bring the pair of end walls together, said peripheral wall having a plurality of axially stacked rows each formed from a plurality of congruent triangular walls equal to twice the number of sides of the polygonal end walls, each row having opposite ends formed by base lines of half of the triangular walls, fold lines connecting the two sides of each triangular wall to the sides of two adjacent triangular walls with the base lines defining spaced parallel polygonal area and each triangular wall having a corner point opposite its base line offset laterally from the base line to turn as the container is collapsed and effect folding of the triangular walls on their fold lines. 
     
     
       2. The container of claim 1 wherein the lateral offsets of the corner points are on a straight line perpendicular to the base and displaced parallel to the tangent of a polygonal circle encompassing the end walls by an amount allowed by deformability of the material forming the triangular walls and the fold lines. 
     
     
       3. The container of claim 2 wherein each corner point is spaced from the base of the triangular wall by a distance having a maximum projection length which is twice the distance of the spacing between said straight line and the tangent of said circle. 
     
     
       4. The container of claim 1 wherein both end walls are rigid. 
     
     
       5. The container of claim 1 wherein the lateral offset of the corner points in adjacent rows is in opposite directions.